Vertex Puratek RO Unit Questions

[Madreefer]

Thanks Albert! So is ok that I changed where my TDS meter is located?

And another question as well as a change of topic.
I have a Alpha Cone 250, I noticed in pics and a vid you have that there is a white adjuster thing on the end of the Red Dragon pumps. What is it for and is this something I should look in to? I have one of the first skimmers that came in to Canada so I guess it's an older version.